35 U.S. Code § 288 - Action for infringement of a patent containing an invalid claim

Whenever a claim of a patent is invalid, an action may be maintained for the infringement of a claim of the patent which may be valid. The patentee shall recover no costs unless a disclaimer of the invalid claim has been entered at the Patent and Trademark Office before the commencement of the suit.

Amendment by Pub. L. 112–29effective upon the expiration of the 1-year period beginning on Sept. 16, 2011, and applicable to proceedings commenced on or after that effective date, see section 20(l) ofPub. L. 112–29, set out as a note under section
2 of this title.